There are increasingly more specs in the OpenID space, and many of the extensions rely on XRDS documents to publicize support. To help enable that, I’ve been looking to update my yadis plugin for WordPress to automatically include the correct protocol support for the major OpenID Providers. Of course, in order to do that I have to actually find out what all protocols they supported, so I pulled out JanRain’s OpenID library and began writing my script. I first checked all the different ways in which you can request an XRDS document… using a request header of Accept: application/xrds+xml, looking for a response header of X-XRDS-Location, looking in the <meta /> tags, etc. Once I had the XRDS document, I checked which protocols they advertised support for, and compiled that all into a nice little table.

See the OpenID Support Table.

The results are about what I would expect… there are just a few front-runners that are really making an effort to support the emerging technology (likely because they are also involved in authoring these new protocols). Everyone else is supporting some version of the (technically, still current) OpenID 1.x protocol and about half have also added sreg support. That same half have basic XRDS support (since it’s required for sreg), but none of them are doing more than the most basic XRDS discovery method. Only a couple of the leaders are supporting the more advanced (and much faster) XRDS discovery.